.0.18 Um Eeprom Products To Read And Write And Solutions

As an important part of Non-Volatile Memory, the electrical erasable programmable read-only memories are more and more widely used. Its application includes smart card, automobile electronics, digital television, digital camera, printer, electrograph and computers, etc. As EEPROM product can be erased and programmed by electronics signal but not by external equipment, and also they can be erased and programmed by byte but not by all content, they are subjected to the favor of a lot of customers.The EEPROM unit is constituted by two transistors, one is the floating gate transistor and the other is the select transistor. Select transistor is used to select the corresponding floating gate while programming and erasing. Floating gate can store electric charges, the quantity of electric charges that stored in the floating gate will influence the threshold voltage(Vt) of the device, and then we can distinguish it as logic '1' or '0'.0.18um EEPROM product produced with current process suffered from some low yield issue and reliability issue. The main problems are checkboard failure issue and high temperature data retention issue, etc. Low yield issue and reliability issue have increased the production cost and prevented the product for mass production.A typical EEPROM unit has a two-gate-stack structure, the first poly-gate is covered by the gate oxide and inter-poly dielectric (IPD), the gate oxide and IPD are very essential for the data programming, erasing and retention of the EEPROM. The second poly-stack is called the control gate, which is connected to the external electrode. This thesis fixed the checkboard failure issue and high temperature data retention issue by improving the quality of tunnel oxide and IPD and improving the etch process of floating gate to reduce the etching-damage of poly-silicon. This thesis also optimized the spacer etch process to reduce the damage to active area. Through the efforts above, the 0.18um EEPROM product can be mass produced with high reproducibility.